The present invention relates to a removable inspection hole plug for sealing inspection holes formed in a plurality of enclosures wherein the plug may accommodate differential expansion of the enclosure walls.
It is known in the art to provide enclosure housings which enclose various devices with inspection ports or holes to enable the insertion of instruments, such as a borescope, into the enclosure to inspect or monitor the condition of the enclosed mechanism. Such monitoring typically takes place during maintenance periods for the mechanism. At all other times, the inspection holes must be sealed.
In the case of gas turbine engines, the enclosures typically are double-walled enclosures having fluids on opposite sides of the enclosure walls at different temperatures. When such double-walled enclosures contain fluids at approximately the same temperature, the thermal expansions of the enclosures are very nearly equal and known sealing plugs may be utilized with great effect. However, in instances wherein the double-walled enclosures come into contact with fluids at different temperatures, the thermal expansions of the enclosure walls will be unequal to such an extent that a single plug no longer is adequate to simultaneously seal the two inspection ports in the double walls.
French Patent No. 2,510,180 discloses an inspection hole plug for a gas turbine engine wherein sealing elements are integrally joined together. Such integral construction of this plug restricts the applicability of this design in resolving the aforementioned problem of differential thermal expansion.